Im pulling my hair out here. HELP

[dnoftz]

So Im going crazy. The more I read about jetting the more confused I get. So here I go again.

My motor is bored 40 over I will be running a vented air box with uni filter. My exhaust is a FMF Fatty with FMF Power core.

So should I buy a jet kit or can i just buy bigger main jets? Can i just change my main jets and leave the rest stock? any help is appreciated

If a jet kit is a Dynojet kit MQ419 an ok one to go with?

 

[xKroniK13x]

I have a toomey full pipe, vents, and uni filter. About the same mods. Current jet is 310 the rest stock. I'd say 310 is on the bigger side. But you're looking around a 300. So you could buy that, plug chop, and see what she says. You could even start with like a 270. That's what a lot of people run with just the fmf pipe.

 

[blasterfreek30]

dont bother buying a jet kit..u need a couple main jets, mabe a 280, 290, and a 300...and leave the stock pilot

 

[dnoftz]

Cool. I appreciate all the info. That's why I love this site. I could easily be tricked in to buying a $60.00 kit I dont need. Thanks guys.

 

[sicivicdude]

So Im going crazy. The more I read about jetting the more confused I get. So here I go again.

My motor is bored 40 over I will be running a vented air box with uni filter. My exhaust is a FMF Fatty with FMF Power core.

So should I buy a jet kit or can i just buy bigger main jets? Can i just change my main jets and leave the rest stock? any help is appreciated

If a jet kit is a Dynojet kit MQ419 an ok one to go with?

The ONLY "jet kit" you would want to bother with is the vito's JK200 and that's because it provides "standard" mikuni jets (versus dynojet jet numbers which don't cross to ANYTHING) and a replacement thinner needle. The vito's JK200 kit is a 290, 300, 310, 320, 330, and 340 main jet, a replacement needle, and a 30 pilot jet (which most people don't use)

The "staged" jet kits (think FMF or dynojet "stage 1" "stage 2" "stage 3") are a complete waste of time. Either the main jet numbers are proprietary or unmarked either way, you cannot base your numbers off any starting position or report your current jetting if you run into problems with any accuracy at all.

dont bother buying a jet kit..u need a couple main jets, mabe a 280, 290, and a 300...and leave the stock pilot

Depending on his elevation, you've hit the needle on the head. FMF, procircuit, DG, so on and so forth all are going to need right about a 300-290 main in the summer months. Toomey provides a 310 with their kit which seems to be about right for that particular pipe.

 

[chumley1/17/96]

yea dont buy a jet kit its a waste of money just buy the jets you need from a shop.

 

[jaddict]

I have similiar mods . With it being so cold out(30-40s), I'm running a 340 main stock pilot and 4th notch on the needle. plug chop is perfect. I imagine in the summer I will be down a few main jets like a 310

 

[sicivicdude]

I have similiar mods . With it being so cold out(30-40s), I'm running a 340 main stock pilot and 4th notch on the needle. plug chop is perfect. I imagine in the summer I will be down a few main jets like a 310

If your plug chop is perfect, you might want to do a leakdown test just to make SURE you don't have an airleak. A 30 number jump from summer to winter is quite a lot and COULD be pointing to an airleak.

Or you could pull your carb and check your float level, a low level of fuel in the carburetor would need a larger main jet for the vacuum to pull up the proper amount of fuel.

 

[jaddict]

If your plug chop is perfect, you might want to do a leakdown test just to make SURE you don't have an airleak. A 30 number jump from summer to winter is quite a lot and COULD be pointing to an airleak.

Or you could pull your carb and check your float level, a low level of fuel in the carburetor would need a larger main jet for the vacuum to pull up the proper amount of fuel.

If I had a air leak wouldn't it run like crap? Bowl seems to have plenty of fuel in it.

 

[Surfrjag]

It could run fine with the airleak if its fairly small and you jet to it and the only way to know if your float is right is to measure it.